FIG. 5 illustrates an example of a conventional semiconductor light emitting device (See Patent Document 1, for example). The illustrated semiconductor light emitting device X includes a lead 91 and an LED chip 92 mounted on the lead. The lead 91 is formed with a recess, in which the LED chip 92 is received. The recess is defined by a flat bottom surface and a side surface 91a flaring toward the top. The LED chip 92 is bonded to the bottom surface of the recess with silver paste. The side surface 91a serves as a reflector for reflecting the light emitted from the LED chip 92. The lead 91 and the LED chip 92 are covered with light transmitting resin 94. The light transmitting resin 94 forms a lens 94a facing the LED chip 92. The LED chip 92 includes a GaAs substrate and a light emitting layer 92a formed on the GaAs substrate. The light emitted from the light emitting layer 92a travels upward directly or after the reflection at the reflector 91a and is then emitted to the outside of the semiconductor light emitting device X through the lens 94a. 
The semiconductor light emitting device X has room for improvement in the following points. Firstly, because of the structure of the LED chip 92, the light emitted travels only toward the space in front of the light emitting layer 92a. Thus, the portion of the reflector 91a which is close to the bottom surface of the recess does not help the light travel toward the lens 94a, and hence, is useless. Secondly, part of the light emitted from the light emitting layer 92a is totally reflected at the surface of the light transmitting resin 94 to return to the LED chip 92. The returning light is absorbed by the. GaAs substrate of the LED chip 92, which deteriorates the light emission efficiency of the semiconductor light emitting device X. Thirdly, the luminance of the light from the LED chip 92 can be increased by increasing the input power. In this case, however, a larger amount of heat is generated at the LED chip 92. Since the LED chip 92 is covered with the light transmitting resin 94, it is difficult to properly dissipate the heat.
Patent Document 1: JP-A-2006-303184